pinctrl: sh-pfc: r8a7796: Use new macros for non-GPIO pins

Update the R-Car M3-W pin control driver to use the new macros for
describing pins without GPIO functionality.  This replaces the use of
physical pin numbers on the R-Car M3-W SiP (in 39x39 BGA package) by
symbolic enum values, referring to signal names.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>